This looks really cool.

Could 4 sensors be connected to a single Netduino Plus 2? I am thinking of using a set to collect simultaneous data at the same time; 4 are lined up within 1" of each other, pointing at the sky, and when something rolls over each one, the Datetime could be saved/displayed for each acquisition.

I am still digging....

 

I saw this tutorial : http://bildr.org/201...ensors-arduino/ and it is leading me to believe that I can get this to work:

 

https://www.sparkfun.com/products/246

 

the same as this :

 

http://www.mouser.co...pb%2bGHLi3qmps=

 

Is that true? The track is running indoors in a US school gymnasium (lights are fluorescent and 15+ meters in the air) so I think there should be no IR interference.

 

All comments welcomed, I don't want to buy the wrong sensors twice! 

 

 

 

For this kind of derby race, cars run on top of wood guides. My plan was to drill small holes in a section of the track (image shows pink dots where holes could go), place the sensors there, and detect the shadow of the car as it passes over the holes. The crowd watching the race does not have an obscured view of the finish line. Cars have strict requirements about weight and dimensions and add-ons, so they cannot have anything added to them like reflective tape.There is approximately 3mm between the bottom of the car and the wood guide, so my plan was to drill small holes in each slot, embed the sensor in the hole, and run wiring though the hole and under the bottom of the track.

 

I thought that a light sensor would fit these requirements the best, detect when a shadow is cast over a sensor and mark the time.

 

As you can see, I am now having trouble with the detection part....

 

If I went with https://www.sparkfun.com/products/246 , what other hardware would I need to go with it? The video at seems to indicate it can accurately/quickly detect the difference between light and shadow.

 

I am also looking through stuff at Mouser (http://www.mouser.co...nsistor&FS=True) to get more clue.

 

All newbie help is very much appreciated!

 

Thanks.

Chris, thanks for taking a look at this. I am putting in a big chunk of the program in the hopes that you can help me think though the right way to do eventing. This is code for a model car race track; a switch is closed and a race starts, when a car passes over a light sensor the time is logged, and if nothing happens in 10 seconds then the time is logged anyway and then a new race heat can begin.

// extraneous code removedpublic class Program{    private static InterruptPort _laneSensor = null;    private static InterruptPort _buttonOnboard ;    private static InterruptPort _gateSwitch = null;    private static Timer _heatTimer;   	 public static void Main()        {            OnboardHardwarePrep();            SensorsReset();            StartGateSwitchPrep();            TimeContainerPrep();            Thread.Sleep( Timeout.Infinite );        }                private static void OnboardHardwarePrep()        {            _ledOnboard = new OutputPort( Pins.ONBOARD_LED, false );            _buttonOnboard =                new InterruptPort ( Pins.ONBOARD_SW1, true , Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeBoth );            _buttonOnboard.OnInterrupt += new NativeEventHandler ( buttonOnboard_Fire );            _ledOnboard.Write ( false );        }                            private static void SensorsReset()        {            try            {                _laneSensor = new InterruptPort( Pins.GPIO_PIN_A1, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeBoth );                _laneSensor.OnInterrupt += new NativeEventHandler( laneSensor_Fire );            }            catch (Exception xxx)            {                Debug.Print( xxx.ToString() );                // Why do I only get the text "System.Exception" and not rich problem info?            }        }                private static void StartGateSwitchPrep()        {            _gateSwitch = new InterruptPort( Pins.GPIO_PIN_D12, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeBoth );            _gateSwitch.OnInterrupt += new NativeEventHandler( gateSwitch_Fire );        }                        static void gateSwitch_Fire( uint data1, uint data2, DateTime time )        {            RaceHeatBegin();        }                            static void RaceHeatBegin()        {            _ledOnboard.Write( true );            TimerCallback timerCallback = new TimerCallback( Tick );            _heatTimer = new Timer( timerCallback , null , 9999 , 9999 );            _laneTimeBegin = Utility.GetMachineTime().Ticks;            _ledOnboard.Write( false );        }                                static public void Tick( Object stateInfo )        {            Debug.Print( "Timer elapsed for the heat (9.999 seconds)." );            buttonOnboard_Fire( 0, 0, DateTime.Now );        }                static void buttonOnboard_Fire( uint data1, uint data2, DateTime time )	    {            try            {                if (null != _heatTimer)                {                    _heatTimer.Dispose();                }            }            catch (Exception xxx)            {                Debug.Print( xxx.Message );            }            TimingLog();            _ledOnboard.Write ( false );       		 }	   	             private static void MessagePrint( string messageToSay )        {            Debug.Print( messageToSay );            buttonOnboard_Fire( 0, 0, DateTime.Now );        }                        static void laneSensor_Fire( uint data1, uint data2, DateTime time )        {            _laneSensor.OnInterrupt -= laneSensor_Fire;            _laneTimesEnd[1] = Utility.GetMachineTime().Ticks;            MessagePrint( "Lane 1 : " + _laneTimesEnd[1] );        }            }

Also, the Micro Framework appears to throw and Exception if a property is assigned to an Interrupt port more than once (a tactic I tried in order to "reset" the hardware). Is that as-designed behavior?

 

Thanks.

Hey All. I have a Netduino Plus 2 with a Sparkfun photocell sensor wired up to Analog1 with a 10k resistor in the mix (equivalent to what you see in http://bildr.org/201...sistor-arduino/).

 

In my program.cs, I can drop a breakpoint at the event that is fired when the interrupt occurs, and after the first time the sensor interrupt occurs, the event is fired "forever", it does not ever stop.

 

After the event fires, I am logging the datetime ticks that the event happened, but then I do not want the event to fire again.

 

What is the proper programming pattern to accept the interrupt/event one time?

 

 

Thanks.

 

 

  Personally, I would use a photo-transistor instead, it is easier to use and it will work much better.  

 

Thanks for the detailed response. I have re-evaluated what I am trying to do... And now am shopping for "photo transistors". My typical part suppliers have been Adafruit and Sparkfun, neither of which appears to carry what you are talking about. Do you have a vendor recommendation?

 

 

Thanks!

...bump...

 

Anyone?

This is a problem for me because I just re-paved my laptop and now cannot seem to get a decent download link for VS 2012 Express, only 2013. Not good to keep this stuff out of sync...

Take a look at the link you posted. VS 2013 is there. VS 2012 updates are there. VS 2012 Express edition for Windows Desktop is not there.

It did... I actually web-searched a bit, read through his stuff, and that is how I landed here and discovered the Netduino platform.   And it was a happy discovery!

 

I plan to attempt something a little different than what Jarrod created.

 

I was thinking of a configuration where space for each sensor is cut into the track, and as a car rolls over them, time is captured (via IR or pressure or sound or something (I need at minimum thousandths of a second precision, prefer ten-thousandths). I am trying to remove the need to have a paired sensor, remove the need to have hardware above/below the finish line. Just something that points "up" and can tell when something is over it.

 

I saw the below sensors via web searches but am not sure if Netduino driver support exists for 4 simultaneous sensors, and if they would actually "work" for that purpose and can be powered by the Netduino itself.

http://www.adafruit.com/products/164

or

http://www.amazon.co...=A10EAPE4CAYC9P

or

https://www.sparkfun.com/products/9375

or ?

The time captured would be displayed on a simple web page and also on a 4-line LCD (reason why I'm leaning towards a Netduino Plus 2).

 

I am also trying to think through how to start the timing (open/close start gate?). The sky is the limit there.

 

I have several months to get this done, so all thoughts appreciated on how to get started properly.

Hey all. I have developed on .NET for years and years (I can recall combining 1.0 and 1.1 assemblies for system deployments and am still in therapy over that). However, I just discovered the MF and Netduino platform is week, and am really excited to try it out for a real world project. I am starting form zero knowledge , but have about 5-6 months to get the project completed. My plan is to capture and display the event timing of wooden model race cars assembled by kids, each car rolls down a "slot" and the one withi the best aerodynamics and gravitational treatment wins. I currently have a flaky electronic race timing system in place, which needs to be replaced. My current idea is to have a weight-sensitive sensor at the starting line in each slot, and have another at the bottom. On a push button signal, I would detect when the weight was released from the start line sensors, detect when each weight was applied to the bottom line sensor, and then diff and display the elapsed TimeSpan. Other than knowing I want a Netduino2+ (so I can eventually post the results over a protocol to a laptop, or show on a web page), and knowing I need to read some books, I don't know what hardware to acquire or direction to take. All ideas appreciated and excuse any obvious ignorance. Thanks!

Thanks for the thoughts and responses.

 

The cars have weight restrictions, so putting things like magnets on them is off-limits. I think that takes me back to the idea of having some kind of sensor facing "up" and detecting when a car passes over them by casting a shadow. The raceway has fluorescent lights, so I think something like embedding a mini photocell (https://www.sparkfun.com/products/9088) might be a good move; but I wonder how long the wiring can be between the cell and the Netduino, what/where resistors need to be, and also if I can read 4 at a time with a Netduino Plus 2.

 

What do you think of using the light-detection strategy and that particular part, which was mentioned on http://johnnycode.co...h-the-netduino/ ?

 

Thanks again.

Paul (and Hanzibal), you have given me a lot to think about. I am going to acquire some hardware now, start with the basics, and come back to this topic. Thanks!

I have seen "premium jumper wires" on several online stores, none seem to e longer than 300cm / 12in. Why is that? Power loss? Potential for signal interference? Thanks.

When I need something "long" (eg 48 inches), would it be ok to use a piece of shielded Ethernet cable, or would that add additional complexity to the job of just making a sound connection? Thanks.

Dave, yes, that is what I am looking for.

This looks like it had promise, once upon a time:

 

https://forum.sparkf...t=16946#p100892

 

but the links from there are long dead.

 

 

I wonder why an LCD-ready enclosure (with a couple of cable glands)  is such a rarity? Is everyone just exposing naked electronics, hoping their cat/dog/kid/curious friend doesn't touch anything?

I have this serial display for connecting to my Netuino 2 Plus:

 

  http://www.amazon.co...0?ie=UTF8&psc=1

 

and now I am looking for a way to properly mount the display. I think what I want is a "bezel", so that any hole I nibble in my plastic case can have finished look. If that is the right term, where should I go for them?

 

 

Thanks.

 

[EDIT]

 

I think I found something. It just took a while for me to determine the keywords needed for the search engines.

 

https://www.oscsys.c...ore/product/253

Like many other newbies/lightweights, I looked around for something permanent-ish to hold my Netduino ][+ with an LCD and/or other gadgets. I followed a link to http://www.thingiverse.com/thing:48939 and uploaded it to www.sculpteo.com, who quoted me ~$80. When an open holder costs more than my device, I am sure I am doing something wrong.

 

So.... Can anyone recommend a "big enough" case for a Netduino Plus 2 in the $20-$30 range? It seems like this should be easier to find than it is. I am sure I am missing something. Or maybe this is a market waiting to be cracked?

 

 

 

Thanks.

Hi Donovan. Both that part and then one at https://www.sparkfun.com/products/9568 seem to require 5V. How did you deal with that?

Thanks.

What would be the benefit/drawback of connecting two Netduino units directly for communication? I have no real application in mind, just thinking that there might be a use to say have a 'mini detect a certain condition and then push a signal to a Plus 2. Just a random thought. All comments appreciated.

 

Thanksk.

 

I apologize for my lack of clarity. I am not asking about PoE. I am asking about using a simple ethernet switch (or hub) with "n" RJ45 twisted pair connections, being able to power a simple light. I understand that there is not a lot of power in each switch port, but I was guessing (hoping?) that maybe using 2-3 of them together could power an LED lamp of some kind. It seems like a simple utilitarian thing, but no one seems to make (or bg about home brew) such a device. Thanks!

There is a remote web server waiting to accept simple HTTP GET traffic and I want to make calls to it from my Netduino Plus 2. I am familar with using WebClient in the .NET Framework, but do not see anything comparable for the Micro Framework.

 

What is the proper way to just send a GET from a Netduino? I just want to send stuff like

 

http://192.168.1.1/g...a=1&b=2&c=3&d=4

 

from the Netduino to my remote web server.

 

 

Thanks

 

.

@qsnapper, thanks for providing input. I was unable to get that to work with my configuration for some reason. I did not have the right reference assemblies loaded up to get those WebClient bits to work.

 

I used  Toolbox.NETMF.NET.HTTP_Client this way:

 var httpClient = new HTTP_Client( new IntegratedSocket( _remoteCollectionSite, 80 ) );                fullUri = _remoteCollectionPath + _paramBuilder.ToString();                HTTP_Client.HTTP_Response httpResponse = httpClient.Get( fullUri  );                Debug.Print( _remoteCollectionSite + fullUri );                Debug.Print( httpResponse.ToString() + "n");

However, if the remote server is not available the exception that comes from a timeout is not easy to trap. I might be having a problem with how Exceptions are caught in my catch{} block because I never get details as I am used to when creating .NET (non Micro) Framework software.

 

Thanks.

I have a Netduino 2+ that will communicate over ethernet. The ND will have a AC power, and the ethernet switch is also powered by AC. I wanted to find an LED lamp that could be powered by the switch, thinking it would be good to have one less thing in my surge protector.... But web searches have turned up nothing as simple as a lamp that can be powered by a typical switch. Can anyone say why no such devices seem to exist? Thanks.